Intra- and interlaminar excitatory synaptic connections of layer 4 spiny neurons and layer 6A pyramidal cells in rat barrel cortex

TL;DRAbstract

In the primary somatosensory (barrel) cortex of rodents, layer 4 (L4) and 6A are the main recipient layers of thalamocortical projections. In addition, a subset of L6A pyramidal neurons provide a direct corticothalamic feedback to the thalamus. Thus, neurons in layer 4 and 6A are an integral part of a thalamo-cortical-cortico-thalamic feedback circuit. To better understand the role of the intracortical unit in this circuit, we studied the anatomical and functional properties of excitatory synaptic connections from layer 4 to layer 6A in the rat barrel cortex by making dual whole-cell recordings with dye injection from L4 spiny neurons and L6A pyramidal cells in acute brain slices. Interlaminar monosynaptic L4-to-L6A excitatory connections (n = 17) were relatively rare. They were of low efficacy with an average excitatory postsynaptic potentials (EPSPs) of 0.32 ± 0.19 mV (n = 17) but of moderately high reliability with failure rate of 24.2 ± 17.7% (n = 16) and coefficient of variation (

Chat with Paper

AI Agents for this Paper